Interlock mechanism



March 3,1959 E. E. SCHWARZENBACH ETAL 2,

INTERLOCK MECHANISM 2 Sheet s-Sheet 1 Filed 001:. 22. 1956 March 3, 1959 E. E. SCHWARZENBACH ET AL 2,

- INTERLOCK MECHANISM Filed 001;. 22, 1956 2 Sheets-Sheet 2 my plh.

United States Patent INTERLOCK MECHANISM Earl E. Schwarzenbach, Niles, and Wilhelm A. Streuer,

Mount Prospect, Ill.,assignors' to Oak Mfg. Co., Chicago, Ill., a corporation of Illinois Application October 22, 1956, Serial No. 617,583 3 "Claims. (Cl. 200-5 This invention relatesto a'n interlock means and more particularly to a three button. interlock mechanism for operating electric switches.

Electric switches operated by a number of interlocked push rods or push buttons are well known. The interlock'action makes'it possible for any one push rod, which is actuated, to'release any previously actuated push rod while at the same time operating a switch for the last actuated push rod. As an example, United States Patent No. 2,213,845, granted on Sepember 3, 1940, shows a multi-button switch having means for interlocking the various push rods. While the construction disclosed in the above identified patent providesa highly desirable ac tion and can be used to accommodate as many push buttons as may be desired, there are occasions when a three button interlock switch is desired.

The construction disclosed in the above identified patent may be readily adapted to threebuttons. However, when used for such a small number of buttons, the construction is relatively expensive to tool. This invention provides a simple and economical three button interlock switch construction which may be economically tooled andeconomically assembled. The construction embodying the present invention consists of sheet metal stampings which may be fabricated to relatively large tolerances.

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type and are here illustrated as of the type having forks 2'3 and 24'associated with suitable snap acting means .so that the switch may be snapped from one position to another. The type of switch illustrated here is widely used. As illustrated here, switches 21 and 22 have their actuating forks 23 and 24fa'cing away from each other. Instead of the switches of the type illustrated above, any other type of switch may be used, such as for example the switches disclosed in United States Patents No. 2,162,- 895, granted'lune 20, 1939, and No. 2,196,433, granted April 9, 1940.

In accordance with the present invention, means are provided for selectively actuating each of the twoswitches while providing an interlock for the remaining switch. If desired, three separate switches may be provided, each switch being actuated by one of three push rods. Three push rods 26, 27 and28 are provided. These push rods are generally similar and may be of flat strip stock with the plane of the strip being disposed generally perpendicular to housing bottom 10. Each push rod is provided with fingers 30 extending downwardly from the bottom edge and lying in slot 31 in bottom 10 of the housing. Slots 31are disposed in parallel relation. Housing 10 is deep enough so that there is substantial room in the housing below the bottom edge of each push rod. Push rods 26 to 28 inclusive have the rear ends In order that the invention maybe understood reference will now be made to the drawing wherein an exemplary embodiment of the inventionis illustrated.

Figure 1 is a top plan view of an interlocked switch construction embodying the present invention.

Figure 2 is a front view of the construction illustrated in Figure 1.

Figure 3 isa view along line 3-3 of Figure 2.

Figure 4 is a sectionalong broken line 4-4 of Figure 1. t

Figure 5 is a-perspective detail of one of the two rocker bars.

"Figure '6 is a perspective view of a switch operating push rod and button.

Figure 7 is a detaitillustratingthe'index means.

The construction --includes base plate 10 having upwardly extending rear wall 11 and upwardly bent front wall 12. The base plate and the two walls may be integral and may be formed of a single piece of sheet steel. The base plate and the two walls form three sides of a housing which is adapted to carry switch supporting plate 15. Switch supporting plate 15 may be made of any suitable material such as insulation material. Switch support plate 15 is provided with a number of fingers 16 adapted to pass through slots 17 in front wall 12 of the switch. Tabs 19 on rear wall 11 of the housing may project through suitable slots in switch supporting plate 15 and these tabs may be staked to lock plate 15 into position.

Plate 15 carries a number of electric switches thereon. As illustrated in Figures 1 and 4, plate 15 carries switches 21 and 22. These switches may be of any suitable projecting through slots 32 inrear wall not the housing. The front portions of the pushrods project through slots 33 in front wall 12 of the housing. As shown in Figure -2, slots '33 and '17 have their lengths at right angles to each other and for convenience may be combined to-provide a cruciform shaped composite slot.

Push rods '26 and 28 are each provided with upwardly extending fingers 35 projecting through slots 36 inswitch supporting plate 15. Push rod 27 does not directly actuate switches 21 and 22 and thus need not be'provided with upwardly extending finger 35. Howevenif electric switches are provided for each switch'rod, finger 35 for each push rod will actuate the electric switches corresponding'to the particular push rod. The front. end of each push rod may be provided with actuating button "37.

The interlock means include a pair of rocking bars 38 and 39 of similar construction. One of these rocking bars is illustrated in Figure 5. Each rocking barconsists of central body portion 40 and cam ends 41 and 42 extending from'opposite parts of the body. Body 40 has aperture 44 through which is adapted to passa pivot finger. Rocking bar 38 has pivot finger 46 and rocking bar 39 has pivot finger'47, each beingpunched up from the metal formingbottom it) of the housing.

rear wall Aperture 44 in each of the rocking bars is large. enough to permitthe rocking bar to turn on each retaining finger. The angleof rocking should be sufficiently great so'that arm portions41 and 42 can be moved toward 10 of the housing. Thus rocker strip 33, as illustrated in full lines in Figure 3, should be movable so that it will have the position corresponding to that shown for rocker 39. The same is true for rocker 39 which should be movable to the position corresponding to that shown for rocker 38. It should be noted that the rockers are below the bottom edge of the push rods and arms 41 and 42 of each of the two rocker strips are in the path of downwardly extending finger 30 of the push rods. Thus push rods 26 and 27 cooperate with the opposite ends of rocker 38. Push rods 27 and 28 cooperate with the opposite ends of rocker 39.

There is also provided rocker plate 50 having clearance openings 51, 52 and 53. Opening 51 is large enough so that plate 50 will always clear downwardly extending finger 30 of the push rod 27. Openings 52 and 53 are provided to permit rocker plate 50 to clear fingers 45 and 46. Rocker plate 50 has end fingers 56 and 57 which cooperate with downwardly extending fingers 30 of push rods 26 and 28 respectively. For convenience, rocker plate 50 is disposed between rocker bars 38 and 39. This, however, is not essential. Rocker plate 50 is movable from the position illustrated in Figure 3 to the reverse position where finger 56 occupies a position corresponding to finger 57.

Downwardly extending fingers 30 of the push. rods cooperate with the front edges of parts 41, 42, 56 and 57 of the rockers. These front edges face the front wall 12 of the housing.

Rocker plate 50 is shaped so that at the rear edge the central part has rounded projection 58. The rocker plate is so dimensioned that projecting part 58 may engage the inside surface of housing wall 11 to limit movement of the rocker plate between front wall 12 and rear wall 11 of the housing.

It may be desirable to provide an index action for any one or all of the push rods. In the form of the invention illustrated in the drawings, switches 21 and 22 are each provided with their own snap acting mechanism. Push rod 27 may be provided with an index means in the form of spring leaf 59 rigidly anchored by rivets 60 to the underside of bottom of the housing. Spring leaf 59 has slot 61 which is somewhat smaller in dimension than slot 31 in wall 10. Finger 30 of push rod 27 is long enough to extend through slot 31 of bottom 10 and cooperate with the end 62 of leaf spring 59. The tip of finger 30 is pointed so that the finger may ride into slot 61 of the leaf spring or may be beyond the end of the leaf spring. Thus as push rod 27 is pushed in, finger 30 will push end 62 of the leaf spring downwardly out of its way and permit the push rod to go to its in position. In such in position, downwardly extending finger 30 of push rod 27 will be beyond the end of the leaf spring. Other index means for the push rod may be provided.

The operation of the mechanism is as follows. First let it be assumed that the mechanism is in the position illustrated in Figure 3. As push rod 27 is pushed in, the bottom finger 30 will engage the adjacent end of rocker bar 39 and rock the same clockwise. Rocker bar 39 will now assume the same position as rocker bar 38 is shown as having. Rocker bar 38 will be moved counterclockwise. The right hand end of rocker bar 39 will thus move downwardly as seen in Figure 3 and cause push rod 28 to move outwardly.

At the same time, push rod 27 will rock bar 38 counterclockwise. From the previous operation of this mechanism, rocker plate 50 is in the position illustrated in Figufe 3. In pushing push rod 27 in, the position of rocker plate 50 is undisturbed. Hence push rods 26 and 28 will now be out and electric switches 21 and 22 will be in corresponding positions due to fingers 35.

If push rod 26 is now operated, rocker plate 50 and rocker bar 38 are both moved clockwise. The right hand part of rocker bar 38 will force push rod 27 outwardly from its previous in position.

various switching combinations are possible.

If each push rod is provided with its own switch means, If the switching means do not include index or snap acting means then it may be desirable to provide an index action for each push rod.

What is claimed is:

1. Interlock means comprising a flat base having front and rear support portions extending perpendicular from the same side of the base, alined slots in said front and rear supportions for accommodating three pushrods disposed laterally of each other in parallel relation, said base having two fingers struck up therefrom between the support portions symmetrically with respect to the center pushrod, a first flat rocker arm loose on said base and symmetrically disposed with respect to said center rod and being oscillatable about an axis passing perpendioularly through the base at the center rod, said first rocker arm having arcuate slots for clearing the base fingers and having an end finger extending beyond the projection of an end rod and having another end finger extending beyond the projection of the remaining end rod, a second rocker arm having end fingers extending beyond the projections of the center rod and an end rod, athird rocker arm having end fingers extending beyond the projections of the center rod and remaining rod, the second and third rocker arms being fiat and having cen tral apertures through which the base fingers extend, one finger going through the second rocker arm and the other finger going through the third rocker arm, said first rocker arm having a large clearance slot in line with the center rod and giving access to the end fingers overlying the center rod, each pushrod having a finger extending perpendicular to the base plate and adapted to engage the front edge as seen from the front support portion along the base to the rear support portion, the center rod finger engaging the fronts of the second and third rocker arms, an end rod finger engaging the fronts of the end fingers of the first and second rocker arms, the remaining end rod finger engaging the fronts of the end fingers of the first and third rocker arms, said pushrods being longitudinally movable from front to rear or reverse, and additional operating fingers carried by the pushrods for controlling means associated with the interlock.

2. Construction according to claim 1 wherein index means are disposed at the flat base and operatively connected with the central pushrod.

3. The construction according to claim 1 wherein a switch supporting panel is mounted between the front and rear portions and beside the flat base, electric switches carried by said panel and fingers disposed on at least the end pushrods for operating said switches.-

References Cited in the file of this patent UNITED STATES PATENTS 2,502,042 Hasselbaum Mar. 28, 1950 FOREIGN PATENTS 641,515 Great Britain Aug. 16, 1950 

